Nose Cannula Heated/Humidified Gas Delivery System

ABSTRACT

A low flow heated/humidified respiratory gas delivery system, especially useful for low flow rates as preferred in the treatment of neonate and other such patients, wherein the respiratory gas is heated and humidified as desired for delivery to the patient and the temperature is monitored at the point of delivery to the patient.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of U.S. application Ser. No.11/846,765 filed Aug. 29, 2007 entitled NOSE CANNULA HEATED/HUMIDIFIEDGAS DELIVERY SYSTEM.

FIELD OF THE INVENTION AND BACKGROUND

This invention relates in general to respiratory care and therapy, and,in particular, to the controlled delivery of heated and/or humidifiedrespiratory gases to a user being so cared for or treated. Moreparticularly, this invention relates to controlling the temperature ofthe gas or gases used for such care or treatment at the point of thedelivery of such gas or gases to the user.

In the administration of heated and/or humidified gas or gases to a useror patient, especially those considered as requiring neonatal care, suchas premature infants and some pediatric patients, it is desirable toclosely control and monitor the temperature at which the gas or gasesare delivered. Such gases may be oxygen, heliox, nitrogen, orcombinations thereof, as well as other gases known to those healthcareproviders or clinicians providing such services. For convenience ofillustration the term “gas” will be used hereinafter, but it is to beunderstood that such term includes a single gas as well as a combinationof gases used in respiratory care and therapy by a user or patient.Also, for purposes of convenience, the term user or patient will bereferred to hereinafter as “patient”.

Respiratory gas delivered to, for example, neonate patients ispreferably delivered at a low flow rate, between about 1 and about 15liters per minute. When heated gas flows through a delivery conduit atsuch low flow rates, the temperature of the gas will decrease in transitto the patient delivery point, resulting in a lower temperature gasbeing applied to the patient and condensate being formed in the gasdelivery conduit. The lower temperature gas can cause irritation of thenares and other discomforts to the patient, as well as reducing the coretemperature of the patient. In addition, the accumulation of condensatecan result in the gas propelling a bolus of condensate into thepatient's respiratory system causing coughing or choking. Accordingly,it is highly desirable that the temperature of the respiratory gas beingdelivered to the patient be controlled at the very point where the gasis being delivered to the patient, to insure that the desired gastemperature is being applied to the patient with the desiredhumidification level. Such controlled delivery will increase thepatient's comfort level, and reduce the amount of condensate heretoforeoccurring in available heated-gas delivery systems.

SUMMARY

The above and other needs are met by a low flow heated/humidifiedrespiratory gas delivery system, especially useful for low flow rates aspreferred in the treatment of neonate and other such patients, whereinthe respiratory gas is heated and humidified as desired for delivery tothe patient and the temperature is monitored at the point of delivery tothe patient. In this manner, the gas temperature can be controlled sothat the temperature of the gas being applied to the patient isaccurately maintained, and the formation of condensate in the deliveryconduit is minimized to reduce accumulation. Patients are believed to bemuch more tolerable of such a treatment, and less likely to bedisengaged therefrom. Fewer adverse reactions, such as abrasions, arebelieved to be incurred, and the patient can still be fed or can eatwithout necessitating the removal or disconnecting of the gas deliverysystem.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the invention are apparent by reference to thedetailed description when considered in conjunction with the drawingfigures, which are not to scale so as to more clearly show the details,wherein like reference numbers indicate like elements throughout theseveral views, and wherein:

FIG. 1 is an illustration of the delivery system wherein a delivery tubeor conduit is coupled with a suitable heater to deliverheated/humidified gas to a patient through a nose cannula;

FIG. 2 is an enlarged partial sectional view of a portion of thedelivery tube or conduit through which heated/humidified gas isdelivered to the nose cannula to illustrate the manner in which therespiratory gas is heated;

FIG. 3 is an exploded illustration of a portion of the delivery tube orconduit through which heated/humidified gas is delivered to the nosecannula for application to the patient;

FIG. 4 is an exploded illustration of another portion of the deliverytube or conduit through which the temperature of the heated/humidifiedgas is monitored at the point of delivery to the patient;

FIG. 5 is an enlarged illustration of a portion of the delivery tube orconduit illustrated in FIGS. 3 and 4 in an embodiment in which the nosecannula is formed with a partition which separates the input ofrespiratory gas to the patient from the sensing of the gas temperaturefor controlling the operation of the heater to better illustrate themonitoring of the temperature of the gas as it is being applied to thepatient, and the path of the air flow;

FIG. 6 is an enlarged illustration of a portion of the delivery tube orconduit illustrated in FIGS. 3 and 4 in an embodiment in which the nosecannula is formed without a partition which separates the input ofrespiratory gas to the patient from the sensing of the gas temperaturefor controlling the operation of the heater to better illustrate themonitoring of the temperature of the gas as it is being applied to thepatient, and the path of the air flow; and

FIG. 7 is an enlarged illustration of a portion of the delivery tube orconduit illustrated in FIGS. 3 and 4 in an embodiment in which the nosecannula is formed with a partition which directs the input ofrespiratory gas in a flow path in direct fluid communication with thegas temperature sensor immediately prior to the gas being applied to thepatient for controlling the operation of the heater to better illustratethe monitoring of the gas temperature and the path of the respiratorygas flow.

DETAILED DESCRIPTION

Referring now to FIG. 1, there is illustrated a respiratory gas deliverysystem 100 wherein a source of suitable respiratory gas (not shown) iscoupled to a connector 8 and passes through a conduit 9 for connectionto a humidification chamber which may be, for example, a reusable or asingle-patient-use humidification or nebulizing chamber 10 through aninlet coupling 11. As is known to those skilled in the art, therespiratory gas may nebulize a liquid, or a liquid with medicant,contained in the chamber 10, or the respiratory gas may be bubbledthrough the liquid if desired, and the heated gas passed from thechamber 10 with, or without, a vapor mist as prescribed by a healthcareprovider or clinician. The temperature of the respiratory gas passingfrom the chamber 10 is heated by means of a heater 15, such as theheater disclosed in U.S. Pat. No. 6,988,497 assigned to Smiths MedicalASD, Inc. of Rockland, Mass.

The heated gas is passed out from the chamber 10 through an outletconnector 12 and passes through a standard flexible delivery tube orconduit 20, for delivery to a patient through a nose cannula 50. Asillustrated in FIG. 2, the delivery tube or conduit 20 may be of thetype disclosed in Anthony V. Beran, et al, U.S. Pat. No. 6,167,883,“MEDICAL AIR-HOSE INTERNAL FLOW HEATER” assigned to the assignee of thepresent invention and the disclosure of which is incorporated herein byreference. As illustrated therein, a flexible ribbon 34 spans the widthof a first portion 20 a of the flexible tube 20, and carries therein aheating element 42, preferably an electrically conductive wire orplurality of wires connected to a power supply in order to heat the flowof gas traveling within this portion of the delivery tube 20 a. Whilethere is illustrated a heater wire 42 carried within the tube 20 by aflexible ribbon 34, the wire 42 may be positioned within the tube 20without being supported by a flexible ribbon such as, for example, bybeing coiled along the interior of the tube 20.

As better illustrated in FIG. 4, the distal portion 42 a of the heatingelement 42 terminates at the entrance into the nose cannula 50, at thepoint at which the heated gas is applied or administered essentiallydirectly to the patient. In this manner, the respiratory gas is heatedall the way through the first portion 20 a of the flexible tube 20 sothat the slow rate of flow of the respiratory gas will not cool the gasbelow the desired temperature, but is applied directly to the patient atthe clinician prescribed temperature level. Maintaining the respiratorygas heated to the prescribed temperature level at the point of deliveryto the patient, will thereby minimize the occurrence of condensateformation.

The temperature of the respiratory gas being delivered to the nosecannula 50 through the flexible tube 20, is controlled by a sensor 60,preferably a thermister, which is carried within a second portion 20 bof the flexible tube 20 extending from an input 13 from the heater 15 toa position within the nose cannula 50 directly adjacent to the point atwhich the respiratory gas is applied or administered, 56, essentiallydirectly to the patient, as best illustrated in FIGS. 5-7. Thepositioning of the sensor in this position, in the nose cannula, willgive direct feedback to the clinician of the temperature of therespiratory gas entering the patient's nose. The output from the sensor60 may, if desired, be coupled to a digital display 65 to provide theclinician with an accurate visual display of the temperature of therespiratory gas as actually being administered to the patient.

Because the air flow is constantly flowing from the outlet 12 of thechamber 10 to the patient's nose cannula 50, only inspiratory air isdelivered to the patient through the first portion 20 a of the flexibletube 20. Accordingly, re-breathing of exhaled air by the patient issubstantially minimized or eliminated entirely.

As best illustrated in the embodiment of FIG. 5, the nose cannula 50 maybe formed with a partition 55 which separates the input of therespiratory gas to the patient from the sensing of the gas temperaturefor controlling the operation of the heater 15. The positioning of thesensor 60 in this manner, in the nose cannula 50 in thermal contact withthe respiratory gas at the point of administration of the gas to thepatient, 56, results in substantially reducing or eliminating the effectthat ambient room temperature and humidity might have on control of thegas temperature and moisture content. It is to be understood, however,that the nose cannula 50 may be constructed without the partition 55separating the input of the respiratory gas to the patient from thesensing of the gas temperature. In such an embodiment the sensor 60,however, is still to be positioned in substantially direct thermalcontact with the respiratory gas at the point of administration, 56, ofthe gas to the patient.

As best shown in the embodiment of FIG. 6, the nose cannula 50 isconstructed without the partition 55, and the sensor 60 is stillpositioned directly adjacent to the point of administration, 56, of thegas to the patient.

The foregoing description of a preferred embodiment for this inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Obvious modifications or variations are possible inlight of the above teachings. The embodiment described has been chosenand described in an effort to provide the best illustrations of theprinciples of the invention and its practical application, and tothereby enable one of ordinary skill in the art to utilize the inventionin various embodiments and with various modifications as are suited forthe particular use contemplated. All such modifications and variationsare within the scope of the invention as determined by the appendedclaims when interpreted in accordance with the breadth to which they arefairly, legally, and equitably entitled.

Also, this application was prepared without reference to any particulardictionary. Accordingly, the definition of the terms used hereinconforms to the meaning intended by the inventors acting as their ownlexicographer in accordance with the teaching of the application, ratherthan any dictionary meaning which is contrary to or different from theinventors' meaning regardless of the authoritativeness of suchdictionary.

Referring now to the embodiment of FIG. 7, the nose cannula 50 isconstructed with a partition 55 a that directs the flow of therespiratory gas in a first flow path of movement directly into contactwith the sensor 60 through which the temperature of the respiratory gasis controlled. The respiratory gas thereafter passes in a second flowpath essentially directly to the cannula outlets 56 for application tothe patient. In this manner the effect that ambient room temperature andhumidity might have on control on the respiratory gas temperature andmoisture control is diminished while obtaining the benefits of thesensor 60 being positioned in substantially direct thermal contact withthe respiratory gas at the point of administration 56 of the gas to thepatient.

1. A method of controlling the delivery of a respiratory gas to a usercomprising the steps of: heating a respiratory gas to a temperaturesufficient to be delivered in a flow path to a user at a predeterminedtemperature level; conveying said respiratory gas to said user at apredetermined flow rate; administering said respiratory gas to said userat said predetermined flow rate and at said predetermined temperaturelevel; and monitoring the temperature of said respiratory gas by passingsaid respiratory gas in a first flow path in thermal contact with atemperature sensor and subsequently in a second flow path essentiallydirectly to said user.
 2. The method of controlling the delivery of arespiratory gas to a user as defined in claim 1 further including thestep of humidifying said respiratory gas to a predetermined level priorto administering said respiratory gas to said user.
 3. The method ofcontrolling the delivery of a respiratory gas to a user as defined inclaim 1 wherein said respiratory gas is administered to said user bymeans of a nose cannula.
 4. The method of controlling the delivery of arespiratory gas to a user as defined in claim 3 wherein the temperatureof said respiratory gas is monitored by a temperature sensor carried bysaid nose cannula.
 5. The method of controlling the delivery of arespiratory gas to a user as defined in claim 4 wherein said sensor ispositioned in direct thermal contact with said respiratory gas moving insaid first respiratory gas flow path.
 6. Apparatus for controlling thedelivery of a respiratory gas to a user comprising: heating means forheating a respiratory gas to a temperature sufficient to be delivered ina flow path to a user at a predetermined temperature level; respiratorygas conveying means for moving said respiratory gas in a first flow pathand in a second flow at a predetermined rate to a user; means foradministering said respiratory gas to said user at said predeterminedflow rate and at said predetermined temperature level; and monitoringmeans in thermal contact with said respiratory gas moving in said firstflow path for monitoring the temperature of said respiratory gas priorto the administration of said respiratory gas in said second flow pathessentially directly to said user.
 7. The apparatus for controlling thedelivery of a respiratory gas to a user as defined in claim 6 furtherincluding humidifying means for humidifying said respiratory gas to apredetermined level prior to administering said respiratory gas to saiduser.
 8. The apparatus for controlling the delivery of a respiratory gasto a user as defined in claim 6 wherein said means for administeringsaid respiratory gas to said user at said predetermined flow rate and atsaid predetermined temperature level includes a nose cannula.
 9. Theapparatus for controlling the delivery of a respiratory gas to a user asdefined in claim 8 wherein said monitoring means for monitoring thetemperature of said respiratory gas is a temperature sensor carried bysaid nose cannula.
 10. The apparatus for controlling the delivery of arespiratory gas to a user as defined in claim 9 wherein said monitoringmeans includes a temperature sensor positioned in direct contact withsaid respiratory gas moving in said first respiratory gas flow path.